Prevention of Type 2 Diabetes: Evidence and Strategies

Similarly, the Finnish Diabetes Prevention Study (FDPS), published in 2001, enrolled 522 middle-aged overweight participants with IGT [23]. The participants randomly assigned to the intervention group received individualized counseling designed to reduce weight, decrease total intake of fat and saturated fat, increase intake of fiber, and increase physical activity. The control group received standard therapy. At 4 years of follow-up, the cumulative incidence of diabetes was 11% in the intervention group and 23% in the control group, with a statistically significant 58% reduction in risk for progression to diabetes. A follow-up of the FDPS was published in 2006 [31]. Participants who did not progress to diabetes in the initial 4-year study were further followed for a median of 3 years. Interestingly, lifestyle changes were maintained by the intervention group participants despite the cessation of the individual counseling, leading to a 36% relative reduction in diabetes incidence during the post-intervention follow-up period alone (4.6 vs 7.2 per 100 person-years, P = 0.041) and a 43% cumulative diabetes incidence reduction over the 7-year follow-up, demonstrating, one more time, the sustained efficacy of lifestyle changes.

In the United States, the Diabetes Prevention Program (DPP) trial is a landmark NIH-sponsored multicenter randomized controlled trial published in 2002, and one of the largest diabetes prevention studies with lifestyle changes to date [24]. A total of 3234 participants with prediabetes, defined as an IFG or IGT, were randomly assigned to an intensive lifestyle modification program, metformin 850 mg twice daily, or matching placebo. Lifestyle changes included a low-fat (< 25% of caloric intake), 1200- to 1800-calorie diet and exercise for 150 minutes a week, with a 7% body weight reduction goal and a very well structured curriculum and professional support group. The study was discontinued early (at 3 years) as the data demonstrated the superiority of lifestyle changes, with a 58% reduction in diabetes incidence in the lifestyle intervention group and a 31% reduction in the metformin group when compared to placebo (cumulative incidence of diabetes at 3 years of 28.9%, 21.7 %, and 14.4% in the placebo, metformin, and lifestyle intervention groups, respectively). Lifestyle changes were significantly more effective than metformin and were consistently effective in men and women across age, BMI, and ethnic groups.

The DPPOS (DPP Outcome Study) was a 10-year follow-up of the DPP study published in 2009 where all participants were offered group-implemented lifestyle changes and were followed for an additional 5.7 years [32]. Unlike the Finnish follow-up study, diabetes incidence was similar in the 3 treatment groups in the follow-up period. However, the cumulative incidence of diabetes remained significantly the lowest in the original lifestyle group, with a 34% cumulative risk reduction in the lifestyle group and an 18% reduction in the metformin group at 10 years when compared to placebo. Interestingly, unlike most other studies of weight-reducing interventions, in the DPPOS, patients in the lifestyle changes and metformin groups maintained weight loss at 10 years’ follow-up.

In Japan, a diabetes prevention study assigned 458 male participants with IGT to a standard intervention group or an intensive intervention group receiving detailed lifestyle modification counseling every 3 to 4 months during hospital visits [25]. The cumulative 4-year incidence of diabetes was 9.3% in the control group versus 3.0% in the intervention group, and the reduction in diabetes risk was 67.4% ( P < 0.001), with body weight reductions of 0.39 kg and 2.18 kg, respectively ( P < 0.001). Of note, participants with higher FBG at baseline developed diabetes at a higher rate than those with lower values. This study suggested that lifestyle change counseling conducted in an outpatient clinic setting can be very effective in preventing diabetes.